Dr. Mirella Vaz, Dr. Mridula Joshi, Dr. Mahesh Ghadage
Professor and Head of Department,
Department of Prosthodontics, Crown & Bridge,
Bharati Vidyapeeth (Deemed to be) University Dental College and Hospital, Navi Mumbai
Defects of the eye may lead to removal of the orbit – part or whole. This can have an immense psychological impact on the self- esteem and personality of the patient. A scleral prosthesis is an artificial replacement of the eye in patients who have an eye defect wherein only a part of the eye has been removed. This case report describes a simple, economical, esthetic, semi- customized method of rehabilitating such a defect with a scleral prosthesis.
Keywords: Scleral prosthesis, iris button, ocular defect, evisceration
Citations: Vaz M, Joshi M, Ghadage M. Rehabilitation of a partial Ocular Defect with Scleral Prosthesis: A Case Report. J Prosthodont Dent Mater 2021;2(2) 55-62
Eye is a vital organ for sight and facial expression. Losing an eye impacts a person psychologically.1 Surgical procedure for eye removal can be categorized as evisceration, enucleation and excenteration. The surgical procedure involving removal of the intraocular contents of the globe and where the sclera, Tenon’s capsule, conjunctiva, extraocular muscles and optic nerve are left undisturbed is called as evisceration. Whereas, when the globe and a portion of the optic nerve is surgically removed from the orbit, it is called as enucleation. Primarily for the eradication of malignant orbital tumors, an en bloc removal of the whole orbit along with partial or complete removal of eyelids is called as exenteration.
The prosthetic rehabilitation of such cases is done either with a prefabricated or custom made ocular prosthesis. The prefabricated ocular shells come in standard sizes, shapes and colors, which could be used for interim or postoperative purposes, but have their drawbacks. On the other hand, custom made ocular prosthesis provide better movement of the eyelids, enhanced fit, comfort and esthetics.
A scleral prosthesis is one technique- sensitive procedure for the accurate duplication of natural color, size, contour and orientation of the eye, which will provide realism and symmetry to the patient. The construction of scleral prosthesis involves a sequence of steps which are critical in the fabrication of a successful prosthesis.2 In this clinical report, a semi- customized scleral prosthesis is fabricated for the rehabilitation of the defect of the eye in a simple and cost- effective approach.
A 73-year-old male patient reported to the Department of Prosthodontics and Crown & Bridge at Bharati Vidyapeeth (Deemed to be) University, Dental College and Hospital, Navi Mumbai, with chief complaint of unpleasing appearance due to defect in the left eye (Figure 1). Patient gave a history of a trauma to his left eye 19 years back, following which he had undergone evisceration of the left eye. Ophthalmic examination, revealed that there were no signs of infection and inflammation. The upper and lower eyelid revealed impaired muscle function. After informing the patient about the procedure and obtaining his consent, a semi- customized scleral prosthesis was planned for the patient.
The patient was prepared for the impression making procedure. This involved lubrication of the eyebrow and eyelashes with petroleum jelly and cleaning the eye socket with saline solution. Primary impression was made using irreversible hydrocolloid impression material (DPI Chromatex Plus, India), by retracting the eyelids and injecting a thin mix of the impression material into the eye space with the help of a syringe.
While the material was setting, the patient was instructed to perform eye movements in all directions to record all the movements of the eye. The patient was then asked to look at a distant spot in the forward direction till the impression material set. A rounded, looped stainless steel wire was engaged into the impression material prior to its setting to aid in removal of the impression from the eye (Figure 2).
After the material was set, it was retrieved from the socket and examined for completeness or any voids. The impression was then poured in type IV gypsum (Pearlstone: Asian Chemicals) and a primary mould was obtained (Figure 3). This mould was used to fabricate the perforated custom tray for the making of final impression (Figure 4).
Final impression was made (Figure 5) using light body elastomeric impression material (Aquasil Ultra LV, Dentsply). After lubricating the eyebrow and eyelashes with petroleum jelly, the impression material was loaded into the eye with the help of the syringe. The material was loaded slowly in order to avoid entrapment of air, starting from the depth below the upper eyelid, proceeding to lower eyelid. The custom tray was then inserted carefully with a thin layer of material. The patient was asked to perform the various eye movements in a similar manner as performed during primary impression making with his gaze fixed straight ahead on some object, such as the handle of the operating light, to ensure that the pupil was well centered.
The impression material, once set, was retrieved carefully from the defect and inspected to ensure that all surfaces were recorded and there was no porosity. (Figure 6). The impression was poured in Type IV gypsum to obtain the two piece final mould with orientation notches (Figure 7).
For fabricating the wax pattern, molten modelling wax was poured in the mould. The wax was carved and contoured giving it adequate bulge to mimic the features of the unaffected eye (Figure 8). The finished wax pattern was then tried in the eye defect and checked for fit, comfort, contour, support and retention by performing the functional movements.
FIGURE 8: WAX TRIAL ON MOULD
The centralization of iris of the left eye was then done (Figure 9). For this, three points were marked on the patient’s face; one in the centre of the forehead between the eyebrows, second at the centre of the iris of the unaffected eye and third equidistant on the left side as per the distance measured between the first and second marked points, when the patient is looking at a distant point in the forward direction. The iris diameter of the unaffected eye was then measured using a round tipped divider and scale (Figure 10) and the wax try-in was done (Figure 11).
The iris for the semi-customized scleral prosthesis was obtained from a prefabricated stock eye and trimmed up to the iris diameter measured of the unaffected eye. The trimmed iris obtained from the stock eye was then incorporated in the wax pattern and tried in the patient’s eye socket and evaluated for orientation of iris. During the try- in, it was ensured that the height of convexity was centered over the pupil, slightly medial to the midline between the inner and outer canthi. The scleral shade was taken using a customized scleral shade guide (Figure 12) which was fabricated using tooth moulding shades (DPI- Heat Cure, Dental Products of India, Ltd.).
Prior to the flasking procedure, an acrylic stump was made to prevent dislodgement of the iris during fabrication (Figure 13). The wax pattern was then flasked, dewaxed and packed with tooth coloured heat cure acrylic resin, according to the shade that was initially selected for the scleral portion in accordance to the contralateral eye (Figure 14,15). Following the curing procedure, finishing and polishing was done of the scleral prosthesis with the iris button in position. Try- in was done to check the fit, comfort, extensions, retention and contour of the prosthesis. Refinement of the scleral prosthesis was done at the try-in stage (Figure 16-18).
Characterization of the prosthesis was then carried out using acrylic colours and woolen fibres to replicate the natural eye. The entire scleral prosthesis was then coated with monomer polymer syrup to keep the woolen fibres in position and allowed to set (Figure 19). In order to create space for the clear acrylic layer, a thin layer of wax was flown over the scleral shell (Figure 20). Flasking, dewaxing, packing and curing of the scleral shell was done using heat cure clear acrylic resin (DPI- Heat Cure, Dental Products of India, Ltd.)
FIGURE 19: CHARACTERIZATION OF THE EYE PROSTHESIS USING ACRYLIC COLOURS AND WOOLEN FIBRES
FIGURE 20: ADAPTATION OF SPACER WAX ON THE CHARACTERISED PROSTHESIS
The prosthesis was then finished and polished and was inserted in the patient (Figure 21(A)(B). Instructions were given to the patient for handling and maintenance of the scleral prosthesis.
Ocular defects may affect the tissues within the ocular cavity or surrounding facial structures depending on the cause of the defect. It may be congenital, acquired or associated with tumors. Early prosthetic rehabilitation of such patients helps in achieving the best esthetic results and psychological advantage to the patient.
The end response to an injury of the eye is called as Phthisis bulbi. It involves deposition of calcium within band keratopathy, sclera, optic nerve or retina.8 The prosthetic rehabilitation can be done using a prefabricated or customized prosthesis. However, the prefabricated ocular prosthesis does not provide a good fit and is generally modified with a tissue conditioner according to the patient’s eye socket. The main drawback of this procedure is that if the unreacted monomer is present, it can cause ulceration and irritation to the conjunctiva. The voids left out after modification of the prosthesis can lead to accumulation of mucus and debris which could irritate the mucosa or even cause infection. These drawbacks can be minimized in a customized prosthesis.
The custom- made prosthesis on the other hand provides a better fit, contour, colour matching and coordinated movement with the contralateral eye. The intimate contact between the prosthesis and the tissue bed helps to distribute the pressure equally, thus, minimizing the chances of ulceration and providing better esthetic outcome.
Acrylic resin is the most commonly used material in the fabrication of scleral prosthesis. It provides adequate longevity, easy to process, noteworthy ageing properties, economical and has minimal maintenance.
In this case report, the patient’s other natural eye was matched and a stock eye with the same iris colour was selected. A customized sclera with the stock iris was fabricated in order to provide a semi customized prosthesis.
Semi- customized Ocular prosthesis provides a better esthetic and functional outcome in comparison with prefabricated or stock eye shell. The artistic skill of the clinician as well as the laboratory technique plays an important role in the success of such prosthesis. In this case report, a simple and economical technique was used to fabricate the Scleral prosthesis to enhance the patient’s appearance, confidence and self- esteem.
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